Thin sheet thrower

ABSTRACT

An apparatus particularly suited for the layup of plywood panels operates to position an individual sheet of veneer over an increasing stack of such veneer sheets. The positioning apparatus consists of a pivoting sheet thrower which is actuated by a hydraulic cylinder to impart an amount of momentum to the veneer sheet sufficient to throw it outwardly over an upwardly inclined tipple. As the veneer sheets leave the end of the tipple they will have a trajectory that is slightly inclined from the horizontal thus tending to prevent bending and which facilitates the placement of each sheet atop the veneer stack.

O United States Patent [151 3,674,256

Brookhyser July 4, 1972 [541 THIN SHEET THROWER Primary Examiner-Even C. Blunk [72] Inventor. Byron B. Brookhyser, Milton, Wash. Assistant Emmmer Bmce H- Smner h [73] Assignee: Weyerhaeuser Company, Tacoma, Wash. Attorney-Patrick D. Coogan, John M. Crawford and Bryan 22 Filed: March 29, 1911 Ogden [21] Appl. No.: 128,778 [57] ABSTRACT An apparatus particularly suited for the layup of plywood U.S. Cl. panels operates to position an individual heet of veneer over 27 V86 an increasing stack of such veneer sheets. The positioning ap- [51] [111. CI ..B65|'l 29/26 paratus consists of a pivoting Sheet thrower which is actuated [58] new of Searchm" "271/69, by a hydraulic cylinder to impart an amount of momentum to 271/70 214/6 D the veneer sheet sufficient to throw it outwardly over an upn R i d wardly inclined tipple. As the veneer sheets leave the end of e the tipple they will have a trajectory that is slightly inclined UNITED STATES PATENTS from the horizontal thus tending to prevent bending and which facilitates the placement of each sheet atop the veneer stack. 1,006,902 10/1911 Bickerton ..214/6 D X 1,140,157 5/1915 Hodgman ..-.....271/86 5 Claims, 2 Drawing Figures Mam THIN SHEET THROWER BACKGROUND OF THE INVENTION This invention relates generally to an apparatus for facilitating the placement of relatively thin sheet material on an increasing stack of such sheet material. More particularly, it relates to a sheet throwing apparatus which is particularly adapted to throwing thin sheets of wood veneer over a layup station in the manufacture of plywood panels.

In the manufacture of plywood panels, core veneer sheets are normally utilized as one of the inner plys. A core veneer sheet is one that has the direction of its grain running parallel to its shorter dimension and is normally of a grade lower than either the face or back veneer sheets. The grain direction of the core sheets is normally positioned transversely to the grain directions of the centers, backs and faces. In such a manner the plywood panel is provided with strength and rigidity. Although the description of the present invention will be made in reference to plywood manufacture, it will be appreciated that the instant invention may be utilized to position material other than wood veneer such as sheet metal, plastic sheets, and the like.

The instant invention is primarily suitable for positioning thin sheets which would otherwise have a tendency to bend about an axis parallel to their direction of travel. The sheets are normally relatively rigid in the direction parallel to travel since with wood veneer sheets, for example, the grain direction as noted is also in the direction of travel.

In prior art devices it was common to allow sheets having the above-noted characteristics to simply be conveyed off the end of the conveyor surface and hopefully they would fall in the proper position onto the stack of sheets. Thus the direction of travel of the leading edge of a conveyed sheet was normally at a downward angle from the horizontal and this allowed substantial bending of the veneer sheets thereby creating a problem with uniform stacking.

Accordingly, from the foregoing, the primary object of the present invention is to improve the stacking characteristics of an individual veneer sheet as it comes from a conveyor surface. Other objects and advantages of the present invention will be realized after taking the following description together with the appended drawings.

SUMMARY OF THE INVENTION Briefly stated this invention is practiced in one form by positioning a thrower member slightly downstream from the end of the conveyor surface and which is arranged and adapted to be sequentially charged with individual sheets of veneer. A hydraulic cylinder then causes the thrower member to pivot an angular distance and with enough momentum to project the veneer sheet a distance further downstream and over an increasing stack of veneer sheets. A properly actuated tipple device gives the veneer sheet a trajectory whereby the plane of the sheet is at an upward angle from the horizontal.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is an isometric view of the present invention with particular areas cut away in section.

FIG. 2 is a side elevation view with particular areas being cut away and showing several veneer sheets in sequential positions as they travel from the conveyor surface to the top of the veneer stack.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawing and to FIG. 1 in particular, the mechanical details of the present invention will be described. Before proceeding it is to be noted that when referring to an element or even that occurs downstream, or upstream" it will be in relation to the travel of a veneer sheet from a point of reference of the channel sections.

A substantially rigid frame is generally indicated at l and provides the necessary support for the various elements of the present invention. Frame 1 is comprised of a pair of upwardly extending channel sections indicated as 2 and 3 respectively with their lower portions being indicated as 4 and 5 respectively and their upper portions as 6 and 7 respectively. The channel sections 2, 3 are timily aflixed to base members 8 and 9 which in turn are secured to ground. Extending in a horizontal upstream direction from the channel sections 2,3 are the horizontal frame members 10 and 11 respectively. The horizontal frame members 10,11 are securely attached to the channel sections 2,3 at a position generally equivalent to the transition section between the lower portions 4,5 and upper portions 6,7 respectively. It should be appreciated that the overall frame 1 is anintegral unit rigidly fixed horizontally, vertically, and laterally.

A portion of the conveyor surface 12 is indicated as extending generally in a horizontal direction upstream from the channel sections 2,3. In FIG. 1 it is shown as being comprised of a plurality of endless flat belts 13 which are trained about a plurality of spaced wheels 14 which are in turn fixedly connected to a rotatable shaft 15. The rotatable shaft 15 may be mounted in a suitable bearing housing 16 which is secured to the horizontal frame member 10 through a mounting bracket 17. Of course an opposite bear-ing member and mounting bracket are provided although they are not shown in FIG. 1. The conveyor surface 12 is powered the direction of the directional arrows and is adapted to convey in an intermittent manner. Any suitable drive means (not shown) may be provided to drive the endless flat belts 13; for example, a motor and drive chain could be interconnected with the rotatable shaft 15.

Between the output end of the conveyor surface 12 which is that portion shown in FIG. 1 and the downstream flange portions 18,19 of the channel sections 2,3 is a laterally extending axial space which has slightly greater dimensions than the dimensions of a veneer sheet. The upstream flange portions of the channel sections 2,3 are indicated as 20 and 21 respectively. Positioned within this axial space is the primary functioning element of the instant invention.

The overall sheet thrower is generally indicated as 22 and extends upwardly and rearwardly from the base members 8,9 to a cocked position which is just below the output end of the conveyor surface 12. Sheet thrower 22. is comprised of a pair of rigid legs 23,24 with a cradle portion 25 extending laterally between the uppermost ends of the legs 23,24. The cradle portion 25 is sized so that as an individual veneer sheet is motivated off the end of conveyor surface 12 the trailing edge portion of the sheet will fall into the cradle portion 25 and be slightly inclined in an upward direction from the horizontal.

Extending from the cradle portion 25 and over the uppermost ends of legs 23,24 is a curvilinear slide surface 25a. Surface 25a is provided in order to support each veneer sheet as it leaves the conveyor surface 12 but before it hits an appropriate stop means. A guide member 26 extends generally between the output end of the conveyor surface 12 and the top of the cradle portion 25 in order to properly guide the trailing edge of an individual veneer sheet as it falls into the cradle portion 25.

Extending between the pair of legs 23, 24 is a rigid tubular member 27. Tubular member 27 is positioned toward the bottom portion of the rigid legs 23,24 and operates to provide both support to the sheet thrower 22 and as the pull bar means for turning the sheet thrower 22 through the proper angle.

In order to provide the proper sheet thrower movement a suitable hydraulic cylinder 28 is mounted on a cross bar member 29 (which extends between the channel sections 2,3) and is operatively connected to the: tubular member 27 through an attachment member 30. The cross bar member 29 has a top attachment member 31 connected to it for the suitable connection thereto of the opposite end of hydraulic cylinder 28. The top attachment member 31 allows the hydraulic cylinder to rotate about its pinned connection 32. In a like manner the attachment member 30 allows the hydraulic cylinder 28 to pivot about its pinned connection 33 on the attachment member 30.

In order to provide the proper angular travel for the sheet thrower 22 and its proper rotational movement a pair of pin connections 34 and 35 respectively are positioned adjacent the lower portions 4,5 of the channel sections 2,3. The pin connections 34,35 for the rigid legs 23,24 allow the sheet thrower 22 to rotate through the proper angle indicated as 7 on FIG. 2 thus allowing the cradle portion 25 to traverse the proper arc of travel. The proper angle 7 is on the order of 40 but may vary within a suitable range (30 to 50 to provide similar operation.

Spanning the distance between the channel sections 2 and 3 at a vertical position slightly below the upper horizontal plane of the flat belts 13 is a pivotal tipple member generally indicated as 36. The proper vertical placement of the pivotal tip ple 36 may be readily seen by referring to FIG. 2. The pivotal tipple 36 is comprised of a channel spanning tubular section 37 and a plurality of fingers indicated as 38. The tubular section 37 is rotatably mounted in a pair of bracket members 39 and 40 respectively which are firmly attached to the upstream flanges 20,21 respectively. Positioned close to the bracket member 39 but comprising an integral part of the tubular section 37 is the pivoting finger 41. Connected to the end of the pivoting finger 41 through a pivotal pin arrangement is the ram 42 of the hydraulic cylinder 43. Hydraulic cylinder 43 is mounted in a generally vertical fashion above the pivoting finger 41 and pivotal tipple 36 such that on a controlled command it will cause the fingers 38 to rotate through an angle indicated as a on FIG. 2 and which is on the order of 30-40. When the ram 42 is in the extended position the fingers 38 are generally horizontal-in position and on the command signal the ram 42 will pivot the fingers 38 upwardly through the angle a. The opposite end of the hydraulic cylinder 43 is pivotally fixed at a position on the upper portion 6 of the channel section 2.

Positioned axially downstream from the pivotal tipple 36 is the vertically extending thrower backstop 44. The thrower backstop 44 is comprised of suitable material in order to stop the forward movement of an individual veneer sheet as its conveyor momentum carries it over surface 25a and across the axial space between the channel sections 2,3 and conveyor surface 12. It may have a slightly rounded top portion 45 to provide smooth flow as a veneer sheet is thrown outwardly by sheet thrower 22. The vertical height of thrower backstop 44 is designed so as to operate in conjunction with the pivotal tipple 36. When the fingers 38 are in the horizontal position, a portion of the thrower backstop 44 is exposed to incoming veneer sheets. After the veneer sheet has hit the backstop 44 and fallen into the cradle portion 25 of thrower 22 and the fingers 38 have been moved to their upper position through the hydraulic cylinder 43, a plane extending generally downstream along the top surfaces of the fingers 38 will pass slightly over the top of the rounded portion 45. A more complete understanding of this action will be gained after referring to the Operation of the Invention.

As the veneer sheets leave the sheet thrower 22 means must be provided for collecting and stacking each veneer sheet. In order to accomplish this function a vertically extending backstop 46 is placed a suitable distance downstream from the thrower backstop 44. The backstop 46 is high enough so that each veneer sheet as it leaves the sheet thrower 22 will be stopped by a cushion of air which is contained by backstop 46. Adjacent the backstop 46 is a stacking table or layup table 47 which is sufficient in width to accommodate the shorter dimension of the veneer sheets. The stacking table 47 may be of the type which is vertically adjustable. To complete the stacking area means a backstop 48 is positioned an appropriate distance from backstop 46 and axially adjacent to the thrower backstop 44.

In the normal course of operation two human operators will be positioned on either side of the stacking table 47 in order to more accurately guide the incoming veneer sheets to a position atop the increasing stack 49. At the same time if a straight edge to the veneer stack 49 is desired the human operators cause each veneer sheet to closely abutt backstop 48.

OPERATION OF THE INVENTION Before proceeding with a description of the operation it is to be noted that a suitable control system will be required to operate the various moving elements but after a full description of the operation it will be readily apparent to one skilled in the art that the various steps in the operation may be readily controlled by either hydraulic means and/or electrical means.

Assuming that an individual veneer sheet has been placed on the conveyor surface 12 at some position upstream from the output end it will then be ready to be conveyed downstream toward the sheet thrower 22. The conveyor surface 12 is powered and will convey the veneer sheet with sufficient momentum to propel it outwardly from the output end and toward the thrower backstop 44 in a generally horizontal direction. The veneer sheet will slide over the surface 25a and across the fingers 38 and then will contact the backstop 44 and this impact will halt its forward motion and cause it to fall back and into the waiting cradle portion 25 which, simultaneously with impact retracts. When the veneer sheet is allowed to hit the backstop 44 the fingers 38 will of course be in the horizontal position. Immediately after impact or after the thrower 22 is fully retracted the hydraulic cylinder 43 will pivot the fingers 38 through the angle 0: thus aiding the rearward falling movement of the veneer sheet.

At this point the sheet thrower 22 is charged and ready to propel the individual veneer sheet to a position over the veneer stack 49. Hydraulic cylinder 28 is actuated causing the thrower to turn through the angle -y imparting a sufiicient amount of momentum to the veneer sheet to propel it outwardly over the tops of the fingers 38 and the thrower backstop 44 and toward the backstop 46. After the trailing edge of the veneer sheet clears the ends of the fingers 38 the pivotal tipple 36 is moved to its horizontal position for the receipt of another incoming veneer sheet.

As a veneer sheet is thrown outwardly it will be in a plane which is at an angle inclined upwardly from the horizontal. In this manner, since a thin sheet represents a lifting body the entire plane in both directions will maintain a flat surface as it travels outwardly. In this manner, the bending as mentioned in the Background of the Invention" will be lessened and after the veneer sheet essentially stalls in the air it will fall gently downward to assume the top position on the veneer stack 49. If the human operators are utilized they will clutch either side of the veneer sheet as it falls downwardly and guide it against the backstop 48 in order to provide a straight side to the stack. Backstop 46 is an air stop and operates to prevent gross escape of air from over the stack, thereby improving the trajectory and falling movement of each sheet.

While a detailed example of the principal embodiment has been described it is understood that many changes and modifications may be made in the above described thin sheet thrower without departing from the spirit of the invention. All such modifications are intended to be included within the scope of the appended claims.

What is claimed is:

1. A positioning apparatus for thin sheets comprising:

a substantially rigid frame having at least two spaced apart structural portions,

a pivotally mounted sheet thrower positioned between said structural portions and having a cradle portion for the acceptance of said thin sheets,

means to charge said thin sheets into said cradle portion,

means to pivot said sheet thrower through an angle,

means to accept said thin sheets as they are thrown outwardly by said sheet thrower, and

means to direct said thin sheets to said sheet accepting means as they are thrown outwardly by said sheet thrower. I

2. The positioning apparatus as in claim 1 in which said sheet charging means includes:

conveying means positioned axially upstream from said sheet thrower,

a vertically extending backstop positioned to halt the forward movement of an incoming thin sheet, and

and adapted to pivot said sheet thrower through said angle.

5. The positioning apparatus as in claim 1 in which said sheet accepting means includes:

a stacking table positioned axially downstream from said sheet thrower, a vertically extending airstop positioned adjacent the downstream side of said stacking table, and a vertically extending secondary backstop positioned adjacent the upstream side of said stacking table. 

1. A positioning apparatus for thin sheets comprising: a substantially rigid frame having at least two spaced apart structural portions, a pivotally mounted sheet thrower positioned between said structural portions and having a cradle portion for the acceptance of said thin sheets, means to charge said thin sheets into said cradle portion, means to pivot said sheet thrower through an angle, means to accept said thin sheets as they are thrown outwardly by said sheet thrower, and means to direct said thin sheets to said sheet accepting means as they are thrown outwardly by said sheet thrower.
 2. The positioning apparatus as in claim 1 in which said sheet charging means includes: conveying means positioned axially upstream from said sheet thrower, a vertically extending backstop positioned to halt the forward movement of an incoming thin sheet, and a pivotal tipple adjacent said backstop arranged and adapted to pivot upwardly as each thin sheet impacts against said backstop.
 3. The positioning apparatus as in claim 2 in which said sheet directing means includes said pivotal tipple in its upwardly extending position arranged so as to allow each thin sheet to be thrown over the top of said backstop at an angle inclined from the horizontal.
 4. The positioning apparatus as in claim 1 in which said sheet thrower pivoting means includes an actuating cylinder extending from said rigid frame to said sheet thrower arranged and adapted to pivot said sheet thrower through said angle.
 5. The positioning apparatus as in claim 1 in which said sheet accepting means includes: a stacking table positioned axially downstream from said sheet thrower, a vertically extending airstop positioned adjacent the downstream side of said stacking table, and a vertically extending secondary backstop positioned adjacent the upstream side of said stacking table. 